CN117165103A - Modification method of waste tire thermal cracking carbon black and carbon black obtained by modification method - Google Patents

Abstract

The invention discloses a method for modifying waste tire thermal cracking carbon black and the carbon black obtained therefrom. The method includes: (1) subjecting thermal cracking carbon black to high temperature treatment; (2) adding the thermal cracking carbon black after medium-high temperature treatment in (1) to an acid solution, and stirring to obtain a water suspension of pickled thermal cracking carbon black. The turbid liquid is washed with water and then dried to obtain acid-washed thermal cracking carbon black; (3) The acid-washed thermal cracking carbon black obtained in (2) is mixed with a silane coupling agent and heat-treated to obtain modified thermal cracking carbon black. The modification method of the present invention reduces the ash content of thermal cracking carbon black, enhances its surface activity, improves the reinforcing performance of thermal cracking carbon black in rubber, increases the usage amount of thermal cracking carbon black, and makes thermal cracking carbon black more durable. Black has a wider range of applications.

Description

A modification method for waste tire thermal cracking carbon black and the obtained carbon black

Technical Field

The invention relates to the technical field of modification of waste tire thermal cracking carbon black, and in particular to a modification method of waste tire thermal cracking carbon black and the obtained carbon black.

Background Art

With the development of my country's social economy, cars are increasingly integrated into production and life, and the use of tires is becoming increasingly huge, but with it comes the serious problem of waste tire treatment and reuse. Traditional methods such as direct landfill, refurbishment of old tires, and production of rubber powder have problems such as environmental pollution, narrow scope of application, and waste of resources. The thermal cracking method of waste tires is regarded as an environmentally friendly and efficient treatment method. While disposing of waste tires, it truly achieves "eating dry and squeezing out" and obtains additional products with higher utilization value, which is of great significance. Among them, thermal cracking carbon black, as an important product of the thermal cracking tire process, has long had the problem of poor reinforcement performance, which has restricted the development of the entire thermal cracking industry.

Pyrolysis is the process of converting waste polymers (or biomass) into small molecule compounds and solid products at a suitable temperature in an oxygen-free or inert atmosphere. Research on pyrolysis started early abroad. In the 1970s, Kaminsky and others from the University of Hamburg in Germany began to study the pyrolysis of waste polymers. As for pyrolysis carbon black, in the 1980s, Bouier J.M. of France found that pyrolysis carbon black contained a high ash content and residual pyrolysis oil, and had poor reinforcement properties in rubber. At present, pyrolysis carbon black directly obtained by pyrolysis of waste tires generally needs to be modified to restore its reinforcement properties so that it can be applied to tires, thereby increasing its product added value and application range. However, whether it is ultra-fine modification for the purpose of reducing particle size or simple modifier modification, its reinforcement performance in rubber has been improved, but the improvement is limited, and it is difficult to reach the level required by high-performance carbon black or national standards. In order to ensure product performance, it can only be mixed with a large amount of commercial carbon black, which restricts the use of thermal cracking carbon black; the previous acid washing modification efficiency is low, and strong acid will greatly increase the surface activity of thermal cracking carbon black, and it is easier for carbon black particles to agglomerate, which reduces the dispersion of carbon black in rubber, thereby restricting the performance of carbon black rubber composites.

Therefore, there is an urgent need for a modification method that can effectively reduce the ash content of thermal cracking carbon black and avoid the agglomeration problem.

Summary of the invention

In order to solve the problems existing in the prior art, the present invention provides a modification method of waste tire pyrolysis carbon black and the obtained carbon black. The modification method of the present invention comprises: firstly pre-treating the sample by high temperature under nitrogen atmosphere or vacuum, then acid washing to reduce the ash content, and finally adding a coupling agent for grafting modification. The modification method improves the reinforcing performance of pyrolysis carbon black in rubber, increases the usage of pyrolysis carbon black, and makes pyrolysis carbon black have a wider application.

One of the purposes of the present invention is to provide a method for modifying waste tire thermal cracking carbon black.

The method comprises:

(1) subjecting thermal cracking carbon black to high temperature treatment;

(2) adding the thermal cracking carbon black treated at medium and high temperature in (1) to an acid solution, stirring to obtain an aqueous suspension of acid-washed thermal cracking carbon black, washing with water and then drying to obtain the acid-washed thermal cracking carbon black;

(3) The acid-washed thermal cracking carbon black obtained in (2) is mixed with a silane coupling agent and subjected to heat treatment to obtain modified thermal cracking carbon black.

In a preferred embodiment of the present invention,

In step (1),

The high temperature treatment is carried out in a nitrogen atmosphere or under vacuum conditions.

In a preferred embodiment of the present invention,

In step (1),

The high temperature treatment temperature is 300 to 600° C., preferably 400 to 500° C., more preferably 450 to 500° C., and the high temperature treatment time is 15 min to 1 h, preferably 30 min to 40 min.

In a preferred embodiment of the present invention,

In step (2),

The acid solution is one of nitric acid solution, hydrochloric acid solution and sulfuric acid solution;

The concentration of the acid solution is 2 mol/L to 7 mol/L, preferably 3 mol/L to 5 mol/L.

In a preferred embodiment of the present invention,

In step (2),

The mass ratio of the thermal cracking carbon black after high temperature treatment to the acid solution is 1:5 to 1:20, preferably 1:8 to 1:19.5.

In a preferred embodiment of the present invention,

In step (2),

The stirring temperature is 50℃～80℃, and the stirring time is 30min～2h;

The mixture was washed with water until the pH value was 5-6 and then dried.

In a preferred embodiment of the present invention,

In step (3),

The silane coupling agent is a silane polymer containing a polyether chain segment (the silane polymer containing a polyether chain segment of patent application 202111383364.9 is adopted, which is introduced in its entirety herein)

Silane polymers containing polyether segments have the following general formula:

R _x Si _y O _z (OR ₁ ) _w O(R ₂ ) _m Q _n …Formula (Ι)

In formula (I), x is 2 to 12, preferably 2 to 6;

y is 2 to 12, preferably 2 to 6;

z is 2 to 12, preferably 2 to 6;

w is 2 to 24, preferably 2 to 12;

m is 1 to 6;

n is 1 to 24, preferably 1 to 12;

R is a C3-C36 straight chain or branched chain or cycloalkyl or aromatic hydrocarbon group or alkane or alkene group, preferably a C3-C18 straight chain or branched chain alkane group;

_R1 is methyl or ethyl;

R ₂ is a fatty chain containing a polyether structure, and its structural formula is R ₃ -(C ₂ H ₄ O) _k -, wherein R ₃ is a saturated fatty chain of C3 to C18, and k is an integer of 3 to 9;

Q is S or SH.

The above-mentioned silane polymer is obtained by reacting components including a silane compound and a fatty alcohol polyoxyethylene ether. Preferably, the silane compound is selected from sulfur-containing silanes containing methoxy and/or ethoxy groups, and the fatty alcohol polyoxyethylene ether is selected from fatty alcohol polyoxyethylene ethers with a hydroxyl value of 95 to 180.

The preparation method of the silane polymer containing polyether chain segments comprises heating components including a silane compound and a fatty alcohol polyoxyethylene ether to obtain the silane polymer containing polyether chain segments. Preferably, the preparation method specifically comprises the following steps:

Step 1) adding the silane compound to a solvent for hydrolysis to obtain a silane hydrolyzate;

Step 2) the silane hydrolyzate is subjected to polycondensation reaction to obtain a silane polymer;

Step 3) adding the fatty alcohol polyoxyethylene ether to the silane polymer, and heating the polymer to react, thereby obtaining the silane polymer containing the polyether chain segment.

The above-mentioned silane polymer containing polyether chain segments is prepared by a silane coupling agent containing methoxy or ethoxy groups commonly used in industry through a polycondensation reaction between silanols to obtain a silane polymer, which is then reacted with fatty alcohol polyoxyethylene ether to obtain the silane polymer.

In the above preparation method, in step 1):

The silane compound is selected from sulfur-containing silanes containing methoxy and/or ethoxy groups, and specifically can be selected from at least one of Si69, Si75, KH580, KH590 and the like;

The solvent is selected from at least one of water and alcohol, preferably a mixed solvent of ethanol and water; the ratio of ethanol to water in the solvent is 1:50 to 50:1, preferably 1:20 to 20:1;

The amount ratio of the silane compound to the solvent is (1-100):1, preferably (1-50):1, and more preferably (1-10):1;

The hydrolysis temperature is 25 to 35° C. and the hydrolysis time is 1 to 5 hours;

The hydrolysis is also added with a pH regulator, which is selected from at least one of hydrochloric acid, formic acid, acetic acid, sodium bicarbonate, and sodium carbonate, preferably at least one of hydrochloric acid, acetic acid, and sodium bicarbonate; the pH regulator adjusts the pH of the solution to 3-6.

In the above preparation method, in step 2), the temperature of the polycondensation reaction is 0 to 100° C., preferably 25 to 60° C.; the time of the polycondensation reaction is 1 to 10 hours, preferably 3 to 5 hours.

In the above preparation method, in step 3):

The fatty alcohol polyoxyethylene ether is selected from fatty alcohol polyoxyethylene ethers having a hydroxyl value of 95 to 180;

The molar ratio of the fatty alcohol polyoxyethylene ether to the silane compound is (1-6):1, preferably (1-3):1;

The reaction temperature of the heating reaction is 100-150°C, preferably 110-130°C; the reaction time is 1-12 hours, preferably 1-6 hours;

A catalyst is also added to the heating reaction; wherein the catalyst is selected from titanate catalysts, preferably at least one selected from n-butyl titanate, tert-butyl titanate, and isopropyl titanate; the amount of the catalyst is 0.1 to 3% of the total amount of the silane compound and the fatty alcohol polyoxyethylene ether;

The heating reaction is carried out under the protection of an inert gas; after the heating reaction, a vacuum treatment is required, wherein the vacuum treatment temperature is 50 to 80° C., and the vacuum degree in the reaction container is maintained at -0.06 to -0.1 MPa.

In a preferred embodiment of the present invention,

In step (3),

The mass ratio of the acid-washed thermal cracked carbon black to the silane coupling agent is 8:1 to 15:1, preferably 10:1 to 13:1.

In a preferred embodiment of the present invention,

In step (3),

The mixed heat treatment of the pickled thermal cracked carbon black and the silane coupling agent is to mix the pickled thermal cracked carbon black and the silane coupling agent and then heat treat them at 140° C. to 160° C. for 4 to 6 minutes.

Generally, for ease of operation, the mixing process in step (3) is preferably carried out in a high-speed mixer; the heat treatment process in step (3) is preferably carried out during the rubber mixing process, that is, heat-treated together with the rubber material in an internal mixer at 140°C to 160°C for 4 to 6 minutes.

A second object of the present invention is to provide a carbon black prepared by the method of one of the objects of the present invention.

The present invention can adopt the following specific technical solutions:

The method for modifying waste tire thermal cracking carbon black comprises the following steps:

(1) High temperature treatment of thermal cracking carbon black to prepare for subsequent steps.

(2) acid-washing and post-treating the thermal cracking carbon black obtained in step (1): adding the thermal cracking carbon black after high-temperature treatment to an acid solution in proportion, stirring at high speed at 50°C to 80°C for 30 minutes to 2 hours to obtain an aqueous suspension of the acid-washed thermal cracking carbon black, repeatedly washing with clean water to a pH of 5 to 6, and drying to obtain the acid-washed thermal cracking carbon black.

(3) The acid-washed thermal cracking carbon black obtained in step (2) is mixed with a silane coupling agent in a high-speed mixer in a certain proportion, and the modified thermal cracking carbon black is obtained after heat treatment. The heat treatment of the acid-washed thermal cracking carbon black and the silane coupling agent is preferably carried out during the mixing process with the rubber, and the specific steps are as follows: 1) Rubber, carbon black containing a silane coupling agent, zinc oxide, and stearic acid are added in sequence in an internal mixer, and mixed evenly at 50-60°C; 2) The rubber is heat-treated at 140-160°C in the internal mixer for 4-6 minutes and then discharged; 3) After the rubber is cooled to room temperature, the rubber is placed in an open mixer, an accelerator and sulfur are added, and the mixing is evenly performed.

The differences between waste tire pyrolysis carbon black and ordinary carbon black are mainly concentrated in the following aspects: 1. Morphological characteristics and particle size: the edges of pyrolysis carbon black particles are fuzzy, the shape is irregular, the particle size is large and uneven; 2. The BET specific surface area is small and the surface activity is poor; 3. The impurity content is too high, among which the ash content is generally around 16-20%, and its components are mainly metal oxides such as ZnO and non-metal oxides such as _SiO2 .

Compared with direct pickling, the method of high-temperature pretreatment followed by pickling can more efficiently reduce the ash content and improve the pickling efficiency; and then the coupling agent provided by the present invention is used for modification, which can effectively improve the mechanical properties of the thermal cracking carbon black-rubber composite material.

The beneficial effects of the present invention are as follows:

The waste tire pyrolysis carbon black modification method provided by the invention can improve the acid washing efficiency, significantly reduce the ash content, and improve the reinforcing performance of the pyrolysis carbon black in rubber.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an electron microscope image of commercial carbon black N330;

FIG2 is an electron microscope image of unmodified thermal cracking carbon black;

FIG3 is an electron microscope image of thermal cracked carbon black after high temperature treatment at 500°C for 30 minutes in a nitrogen atmosphere;

FIG4 is an electron microscope image of the acid-washed thermal cracked carbon black of Example 5;

Figure 5 is an electron microscope image of thermal cracked carbon black directly pickled with 5 mol/L hydrochloric acid.

DETAILED DESCRIPTION

The present invention is described in detail below in conjunction with specific embodiments and drawings. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

The raw materials used in the examples are all conventional commercially available raw materials.

Table 1. Brands and sources of some raw materials

name supplier Thermal Carbon Black Commercially available Carbon Black N330 Degussa Carbon Black N660 Degussa sulfuric acid Commercially available hydrochloric acid Commercially available Nitric Acid Commercially available

The test instruments and test conditions used in the examples are as follows:

Table 2. Test standards/conditions

Test items Standards/Conditions Carbon black ash content test GB/T3780.10-2017 Vulcanization performance test GB/T9869 Mechanical testing GB/T528-2009 Vulcanized rubber hardness test GB/T6031-1998

Preparation of silane coupling agent:

Silane coupling agent 1:

10.86g (0.02mol) of silane coupling agent Si69 was put into a mixed solvent with a ratio of ethanol to water of 20:1, wherein the amount of mixed solvent to coupling agent Si69 was 1:5, and formic acid was added to adjust the pH to 3, and hydrolyzed at 25°C for 1 hour to obtain a hydrolyzate containing silanol; then the hydroxyl-containing silane coupling agent obtained by hydrolysis was stirred and polymerized at 25°C for 5 hours, and then 11.64g (0.02mol) of fatty alcohol polyoxyethylene ether-9 (hydroxyl value 95-100) and 0.675g of catalyst tetrabutyl titanate were added, the temperature was raised to 130°C and nitrogen was introduced for protection, and the reaction was carried out for 2.5 hours. Finally, the temperature was lowered to 80°C, the system vacuum was maintained at -0.08MPa, and purified for two hours. The obtained silane coupling agent 1 is a compound containing the following general formula:

C ₁₂ H ₂₄ Si ₄ O ₂ (OC ₂ H ₅ ) ₆ O[(C ₂ H ₄ O) ₉ C ₁₂ H ₂₅ ] ₂ S ₈

Silane coupling agent 2

10.86g (0.02mol) of silane coupling agent Si69 was put into a mixed solvent with a ratio of ethanol to water of 20:1, wherein the amount of mixed solvent to coupling agent Si69 was 1:4, and acetic acid was added to adjust the pH to 3, and hydrolyzed at 35°C for 1 hour to obtain a hydrolyzate containing silanol; then the hydroxyl-containing silane coupling agent obtained by hydrolysis was stirred and polymerized at 25°C for 5 hours, and then 17.46g (0.03mol) of fatty alcohol polyoxyethylene ether-9 (hydroxyl value 95-100) and 0.85g of catalyst tetrabutyl titanate were added, the temperature was raised to 130°C and nitrogen was introduced for protection, and the reaction was carried out for 2.5 hours. Finally, the temperature was lowered to 80°C, the system vacuum was maintained at -0.1MPa, and purified for two hours. The obtained silane coupling agent 2 is a compound having the following general formula: C ₁₂ H ₂₄ Si ₄ O ₂ (OC ₂ H ₅ ) ₅ O[(C ₂ H ₄ O) ₉ C ₁₂ H ₂₅ ] ₃ S ₈

Example 1

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 400°C, then kept constant for 15 minutes, and then cooled to room temperature. The thermal cracking carbon black after high temperature treatment was placed in a 3 mol/L hydrochloric acid solution at a ratio of 10 mL (10.5 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4. The acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a high-speed mixer at a mass ratio of 10:1.

The heat treatment process of the pickled thermal cracked carbon black and the silane coupling agent 1 is carried out during the mixing process with the rubber, and the specific operation steps are as follows: 1) Rubber, pickled thermal cracked carbon black mixed with silane coupling agent 1, zinc oxide, and stearic acid are added in sequence in an internal mixer, and mixed evenly at 55°C; 2) The rubber is heat-treated at 150°C in the internal mixer for 5 minutes and then discharged; 3) After the rubber is cooled to room temperature, the rubber is placed in an open mixer, an accelerator and sulfur are added, and the mixture is mixed evenly; 4) The mixed rubber is vulcanized at 145°C to obtain a vulcanized rubber; the formula is shown in Table 3, and the test results of the vulcanized rubber properties are shown in Table 5.

Table 3. Vulcanized rubber formula

Example 2

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 15 minutes, and then cooled to room temperature; the thermal cracking carbon black after high-temperature treatment was placed in a 3 mol/L hydrochloric acid solution at a ratio of 10 mL (10.5 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4; the acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 3

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 30 minutes, and then cooled to room temperature; the thermal cracking carbon black after high temperature treatment was placed in a 3 mol/L hydrochloric acid solution at a ratio of 10 mL (10.5 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is measured and shown in Table 4; the thermal cracking carbon black after acid washing was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 4

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 600°C in a nitrogen atmosphere, and then kept at a constant temperature for 1h, and then cooled to room temperature; the thermal cracking carbon black after high temperature treatment was placed in a 3mol/L hydrochloric acid solution at a ratio of 10mL (10.5g) of acid solution per 1g of carbon black, and stirred at high speed for 1h at 60°C. It was repeatedly washed with clean water to pH=6, and the carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is shown in Table 4; the thermal cracking carbon black after acid washing was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 5

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 hour at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is shown in Table 4. The thermal cracking carbon black after acid washing was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 6

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 8 mL (8.6 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4. The acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 7

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 15 mL (16.2 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4. The acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 8

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 30 minutes at 50°C, and repeatedly washed with clean water until pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4. The acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 9

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 30 minutes, and then cooled to room temperature; the thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 2 h at 80°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed thermal cracking carbon black. The ash content after acid washing was measured and shown in Table 4; the acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 10

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is shown in Table 4. The thermal cracking carbon black after acid washing was mixed with silane coupling agent 2 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 2 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Embodiment 11

The waste tire pyrolysis carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 30 minutes, and then cooled to room temperature. The pyrolysis carbon black after high temperature treatment was placed in a 5 mol/L sulfuric acid solution at a ratio of 10 mL (13 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain acid-washed pyrolysis carbon black. The ash content after acid washing was measured and shown in Table 4. The acid-washed pyrolysis carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 12

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high temperature treatment was placed in a 5 mol/L nitric acid solution at a ratio of 10 mL (13.5 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 hour at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is shown in Table 4. The thermal cracking carbon black after acid washing was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Example 13

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant for 30 minutes, and then cooled to room temperature; the thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 hour at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the acid-washed thermal cracking carbon black. The ash content after acid washing is measured and shown in Table 4; the acid-washed thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 13:1 for heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of pickled thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Comparative Example 1

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C, then kept constant at that temperature for 30 minutes, and then cooled to room temperature. The thermal cracking carbon black after high-temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed at 60°C for 1 hour, washed repeatedly with clean water until pH = 6, and the carbon black was dried to obtain the acid-washed thermal cracking carbon black.

The acid-washed thermal cracked carbon black was added to the rubber according to the formula in Table 3, and the specific operation was as follows: 1) Rubber, carbon black, zinc oxide, and stearic acid were added in sequence in an internal mixer, and the rubber was discharged after mixing at 55°C. 2) The rubber was placed in an open mixer, accelerator and sulfur were added, and the mixed rubber was obtained by sheeting. 3) The mixed rubber was vulcanized at 145°C to obtain a vulcanized rubber. The performance test results of the vulcanized rubber of Comparative Example 1 are shown in Table 5.

Comparative Example 2

Unmodified thermal cracked carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 and subjected to heat treatment.

The formula and specific operation used in the heat treatment process of the mixture of unmodified thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Comparative Example 3

The waste tire pyrolysis carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 30 minutes, and then cooled to room temperature.

The high-temperature treated thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 4

The waste tire thermal cracking carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then the temperature was kept constant for 30 minutes, and then cooled to room temperature. The high-temperature treated thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The high temperature treated thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 5

The thermal cracking carbon black was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water until the pH value was 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing is shown in Table 4;

The acid-washed thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 6

The thermal cracking carbon black was mixed with 10 mL (10.8 g) of acid solution per 1 g of carbon black and placed in a 5 mol/L hydrochloric acid solution, stirred at high speed at 60°C for 1 h, and repeatedly washed with clean water until the pH was 6. The carbon black was dried to obtain the thermal cracking carbon black after acid washing. The ash content after acid washing was measured and shown in Table 4; the thermal cracking carbon black after acid washing was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The acid-washed thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 7

The experiment was conducted by reversing the order of step (1) and step (2), as follows:

The thermal cracking carbon black was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed at 60°C for 1 h, washed repeatedly with clean water until pH = 6, and the carbon black was dried to obtain the acid-washed thermal cracking carbon black; the acid-washed thermal cracking carbon black was placed in a muffle furnace, and the temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C and then kept constant for 30 min, and then cooled to room temperature. The ash content after modification was measured and shown in Table 4;

The modified thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 8

The experiment was conducted by reversing the order of step (1) and step (2), as follows:

The thermal cracking carbon black was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed at 60°C for 1 h, washed repeatedly with clean water until pH = 6, and the carbon black was dried to obtain the acid-washed thermal cracking carbon black; the acid-washed thermal cracking carbon black was placed in a muffle furnace, and the temperature of the muffle furnace was increased from room temperature at a rate of 10°C/min in a nitrogen atmosphere to 500°C and then kept constant for 30 minutes, and then cooled to room temperature. The ash content was measured after modification and is shown in Table 4; the treated thermal cracking carbon black was mixed with silane coupling agent 1 in a mass ratio of 10:1 for heat treatment.

The formula and specific operation of the mixed heat treatment process of modified thermal cracking carbon black and silane coupling agent 1 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Comparative Example 9

The waste tire pyrolysis carbon black was weighed and placed in a muffle furnace. The temperature of the muffle furnace was raised from room temperature at a rate of 10°C/min to 500°C in a nitrogen atmosphere, and then kept at a constant temperature for 30 minutes, and then cooled to room temperature; the pyrolysis carbon black after high temperature treatment was placed in a 5 mol/L hydrochloric acid solution at a ratio of 10 mL (10.8 g) of acid solution per 1 g of carbon black, stirred at high speed for 1 h at 60°C, and repeatedly washed with clean water to pH = 6. The carbon black was dried to obtain the acid-washed pyrolysis carbon black. The ash content after acid washing was measured and shown in Table 4; the acid-washed pyrolysis carbon black was mixed with Si69 at a mass ratio of 10:1.

The formula and specific operation of the mixed heat treatment process of modified thermal cracking carbon black and silane coupling agent Si69 and the performance of modified thermal cracking carbon black in rubber are the same as those in Example 1; the test results of the vulcanized rubber properties are shown in Table 5.

Comparative Example 10

The ash content of the unmodified thermal cracking carbon black was measured, as shown in Table 4. The unmodified thermal cracking carbon black was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1, and the obtained rubber properties are shown in Table 5.

Comparative Example 11

Carbon black N330 was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1. The properties of the obtained rubber are shown in Table 5.

Comparative Example 12

Carbon black N660 was added to the rubber according to the formula in Table 3 and the specific operation of Comparative Example 1. The properties of the obtained rubber are shown in Table 5.

Table 4 Carbon black ash content

Table 5 Rubber properties

It can be seen from Comparative Examples 3 and 4 that, although the tensile strength of the rubber composite material is improved by only high-temperature treatment or adding a coupling agent after high-temperature treatment, the tensile strength will decrease significantly at the same time; it can be seen from Comparative Examples 5 and 6 that the ash content is reduced slightly by directly modifying the thermal cracking carbon black by pickling or adding a coupling agent after pickling, the pickling efficiency is not high, and the mechanical properties of the rubber composite material are improved slightly; the ash reduction effects obtained by using the same pickling treatment conditions under different high-temperature treatment conditions in Example 1, Example 2 and Example 3 are quite different, indicating that sufficient high-temperature treatment can improve the pickling efficiency. Results; From Table 4, it can be seen that after high-temperature treatment, sufficient acid solution treatment can effectively reduce the ash content of thermal cracking carbon black; In Comparative Examples 7 and 8, the order of acid washing and high temperature is reversed, the ash content is reduced less, and the acid washing efficiency is low, which proves the importance of the experimental order in the present invention; From the data in Table 5, it can be seen that the method for treating waste tire thermal cracking carbon black provided by the present invention can effectively improve the tensile strength and hardness of the thermal cracking carbon black-rubber composite material under the premise of maintaining a high tensile strength, reaching a higher reference sample level (referring to a level exceeding N660 and close to N330), and improving the reinforcing performance of thermal cracking carbon black in rubber materials. Comparative Example 9 Although the high-temperature heat treatment and acid treatment steps are the same as those of the present application, the silane coupling agent for the final mixed heat treatment is not the silane coupling agent of the present invention, and the mechanical properties of the carbon black-rubber composite material are reduced.

As can be seen from Figures 1 and 2, compared with commercial carbon black, the surface morphology of thermal cracking carbon black has larger and uneven particle sizes, blurred particle edges, different shapes, and sticking to each other. As can be seen from Figure 3, after high-temperature heat treatment, the edges of thermal cracking carbon black particles become clear and appear spherical. As can be seen from Figures 4 and 5, high-temperature heat treatment under a nitrogen atmosphere before pickling can effectively improve the pickling effect. The microscopic morphology of thermal cracking carbon black after pickling is closer to commercial carbon black, the impurity coverage is significantly reduced, there are more pores between aggregates, and the characteristics of nanoparticles are more obvious.

Claims (10)

1. A modification method of waste tire thermal cracking carbon black is characterized by comprising the following steps:

(1) Carrying out high-temperature treatment on the thermal cracking carbon black;

(2) Adding the thermal cracking carbon black subjected to the high-temperature treatment in the step (1) into an acid solution, stirring to obtain an aqueous suspension of the acid-washing thermal cracking carbon black, washing with water, and drying to obtain the acid-washing thermal cracking carbon black;

(3) And (3) mixing the acid-washing thermal cracking carbon black obtained in the step (2) with a silane coupling agent for heat treatment to obtain the modified thermal cracking carbon black.

2. The modification process of claim 1, wherein:

in the step (1), the step of (a),

the high temperature treatment is performed under nitrogen atmosphere or vacuum condition.

3. The modification process of claim 1, wherein:

in the step (1), the step of (a),

the high temperature treatment temperature is 300-600 ℃, preferably 400-500 ℃, and the high temperature treatment time is 15 min-1 h, preferably 30 min-40 min.

4. The modification process of claim 1, wherein:

in the step (2), the step of (C),

the acid solution is one of nitric acid solution, hydrochloric acid solution and sulfuric acid solution;

the concentration of the acid solution is 2mol/L to 7mol/L.

5. The modification process according to claim 4, wherein:

in the step (2), the step of (C),

the mass ratio of the thermal cracking carbon black after the high-temperature treatment to the acid solution is 1:5-1:20.

6. The modification process of claim 1, wherein:

in the step (2), the step of (C),

stirring at 50-80 deg.c for 30 min-2 hr;

washing with water to pH 5-6, and drying.

7. The modification process of claim 1, wherein:

in the step (3), the step of (c),

the silane coupling agent is a silane polymer containing polyether chain segments and has the following general formula:

R _x Si _y O _z (OR ₁ ) _w O(R ₂ ) _m Q _n … … (I)

In the formula (I), x is 2 to 12, preferably 2 to 6;

y is 2 to 12, preferably 2 to 6;

z is 2 to 12, preferably 2 to 6;

w is 2 to 24, preferably 2 to 12;

m is 1-6;

n is 1 to 24, preferably 1 to 12;

r is C3-C36 straight-chain or branched or cycloalkyl or aralkyl or olefine, preferably C3-C18 straight-chain or branched alkyl;

R ₁ methyl or ethyl;

R ₂ is a fatty chain containing polyether structure, and has a structural formula of R ₃ -(C ₂ H ₄ O) _k -, where R is ₃ Saturated fatty chain of C3-C18, k is an integer of 3-9;

q is S or SH.

8. The modification process of claim 7, wherein:

in the step (3), the step of (c),

the preparation method of the silane polymer containing the polyether chain segment comprises the steps of heating and reacting components comprising silane compounds and fatty alcohol polyoxyethylene ether to obtain the silane polymer containing the polyether chain segment.

9. The modification process of claim 1, wherein:

in the step (3), the step of (c),

the mass ratio of the acid-washing thermal cracking carbon black to the silane coupling agent is 8:1-15:1, preferably 10:1-13:1;

the mixed heat treatment of the acid-washing thermal cracking carbon black and the silane coupling agent is that the acid-washing thermal cracking carbon black and the silane coupling agent are mixed and then heat treated for 4 to 6 minutes at 140 to 160 ℃.

10. A carbon black prepared by the method of any one of claims 1-9.